Biology Chapter 15-16
Mendel's work on inheritance was published after Darwin's lifetime. T or F
False
Mutation - they always affect an organism's fitness. t or f
False
Mutation- they always affect an organism's phenotype. T or F
False
Mutations - they always affect lengthy segments of a chromosome. Tor F
False
If a trait made an organism less likely to survive and reproduce, what would happen to the allele for that trait?
Fewer copies of the allele would pass to future generations and the allele could even disappear from the gene pool completely.
List three fields that collaborate today to explain evolution.
Genetics, molecular biology, evolutionary theory
Which two important factors was Darwin unable to explain without an understanding of heredity?
He was unable to explain the source of variation and how inheritable traits were passed from one generation to the next.
If a trait had not affect on an organism's fitness, what would happen to the allele for that trait?
The allele would not be under pressure from natural selection and its frequency would remain unchanged.
Most inheritable differences are due to gene shuffling that occurs during the production of gametes. t or f
True
Mutations - they can be limited to a single base of DNA. T or F
True
What is mutation
a change in the DNA sequence
List three ways that reproductive isolation occurs
behavioral isolation, geographic isolation and temporal isolation
List three ways that natural selection can affect the distributions of phenotypes.
directional selection, stabilizing selection, disruptive selection
what is an example of temporal isolation
each of three similiar species of orchid in the same rain forest releases pollen on different days
What is an example of founder effect?
evolution of several hundred species of fruit flies found on different hawaiian islands
A gene pool typically contains just one allele for each inheritable trait. T or F
false
Most traits are controlled by a single gene. t or f
false
Natural selection is the only source of evolutionary change. t or f
false
The basic mechanisms of evolutionary change cannot be observed in nature. t or f
false
The weight of human infants at birth is under the influence of disruptive selection. t or f
false
geographic barriers guarantee the formation of new species. t or f
false
individuals in different species can have the same gene pool. t or f
false
natural selection on single-gene traits cannot lead to changes in allele frequencies. t or f
false
sexual reproduction - it can change the relative frequency of alleles in a population t or f
false
the hypothesis about evolution of galapagos finches that was tested by the Grants - the different finch species are the descendants of a common mainland ancestor. t or f
false
the hypothesis about evolution of galapagos finches that was tested by the Grants - the evolution of the finches is proceeding slowly and gradually. t or f
false
were these observations observed by the Grants - big-beaked birds tend to mate with small-beaked birds. t or f
false
were these observations observed by the Grants - differences in beak size were more important for survival during the wet season. t or f
false
were these observations observed by the Grants - when food for finches was scarce - individuals with the largest beaks were less likely to survive. t or f
false
A situation in which allele frequencies change as a result of the migration of a small subgroup of a population is known as the ________
founder effect
complete the flowchart to show how speciation probably occurred in the Galapagos finches
founders arrive separation of populations changes in the gene pool reproductive isolation ecological competition continued evolution
The situation in which allele frequencies remain constant is called _______
gene equilibrium
The combined genetic information of all members of a particular population is a (an)
gene pool
Random change in allele frequencies in small populations is called ______
genetic drift
Why is large population size important in maintaining genetic equilibrium
genetic drift has less effect on large populations
Abert and Kaibab squirrels in the southwest are an example of _____________ isolation
geographic
Directional - what is the situation
individuals at one end of the curve have higher fitness than individuals in the middle or at the other end.
disruptive - what is the situation
individuals at the upper and lower ends of the curve have higher fitness than individuals near the middle.
stabilizing - what is the situation
individuals near the center of the curve have higher fitness than individuals at either end.
label the two graphs to show which one represents a single-gene trait and which one represents a polygenic trait.
looks like a big hill - polygenic trait looks like bar graphs - single-gene trait
draw a graph that shows how disruptive selection affects beak size.
looks like a camel
What does it mean for two species to be reproductively isolated from each other
members of the two species cannot interbreed and produce fertile offspring
why do mutations occur?
mistakes in the replication of DNA or as a result of radiation or chemicals in the environment
When does geographic isolation occur
occurs when population are separated by geographic barriers like rivers mountains, or bodies of water
A collection of individuals of the same species in a given area is a(an)
population
What must happen in order for new species to evolve?
populations must be reproductively isolated from each other
list the five conditions required to maintain genetic equilibrium
random mating, very large population, no movement into or out of the population, no mutations, no natural selection
The number of times that an allele occurs in a gene pool compared with the number of times other alleles occur is called the _________ of the allele
relative frequency
What does the Hardy-Weinberg principle state?
that allele frequencies in a population will remain constant unless one or more factors cause them to change
what is speciation
the formation of a new species
complete the concept map
top is sources of genetic variation then it branches into two - mutations and gene shuffling
Eastern and Western meadowlarks are an example of behavioral isolation. t or f
true
The number of phenotypes produced for a given trait depends on how many genes control the trait. T or F
true
sexual reproduction - it can produce many different genetic combinations t or f
true
sexual reproduction - it can produce many different phenotypes. t or f
true
sexual reproduction - it is a major source of variation in many populations. t or f
true
the hypothesis about evolution of galapagos finches that was tested by the Grants - differences in the finches beak size and shape produce differences in fitness that cause natural selection to occur. t or f
true
the hypothesis about evolution of galapagos finches that was tested by the Grants - the finches beak size and shape has enough inheritable variation to provide raw material for natural selection. t or f
true
were these observations observed by the Grants - average beak size increased dramatically. t or f
true
When does behavioral isolation occur?
when populations are capable of interbreeding but have differences in courtship rituals or other types of behavior
